Graphene-photonic crystal switch

We have designed and analyzed a graphene-based photonic crystal directional coupler working as a switch, which is embedded in a SOI photonic crystal slab with triangular lattice of dielectric rods. The directional coupler has two W1 (one missing row of dielectric rods) waveguides and the coupling region is coated with a graphene nanoribbon with width W=50 nm.We use an electric gate to modify the graphene chemical potential to obtain the desired change of the graphene equivalent permittivity. Thus, we can drive the directional coupler to get its transition from the bar state to the cross state and vice-versa.